Research Roundup (December 2018)

Welcome to another edition of the research roundup (formerly the articles of the month) – a collection of the best medical articles I have encountered in the last couple months. This write up is always accompanied by the BroomeDocs Journal Club podcast, which can be found here.

A total crap study

Tagg A, Roland D, Leo GS, Knight K, Goldstein H, Davis T. Everything is awesome: Don’t forget the Lego. J Paediatr Child Health. 2018. DOI: 10.1111/jpc.14309

I am sure by now everyone has heard about this paper. It has been discussed on news outlets worldwide, and even joked about on the tonight show. I am not sure Casey and I will be able to make it through. 6 pediatricians swallowed lego heads, and their primary outcome was the found and retrieved time score (FART). They did try to standardize this to individual bowel habits, using the stool hardness and transit score (SHAT), which the authors developed. Only 5 of the 6 individuals were able to find the lego head (maybe the best clinical information from this paper is that even motivated, highly trained individuals won’t always find ingested foreign bodies, so we should probably keep that in mind when advising our patients). On average, transit took 1.71 days, with a non statistical trend towards earlier passage in women than men.

Now.. let’s rip our good friends’ excellent paper to shreds in the name of science education. If you follow the approach outlined in the post “evidence based medicine is easy”, the first question you should ask is: Do these patients looks like my patients? The answer is clearly no. I have shared beers with one of the authors, and I can confirm that he is far taller than the average pediatric patient I care for. Also, their sample size was just too small, and they didn’t include a power calculation in their methods section. That being said, they didn’t lose any study participants to follow-up, which is impressive considering what you were asking these folks to do. However, when you consider the dirty task required, I think some objective evidence of retrieval would have increased my confidence in the results, because I could imagine that if I was a study participant, I would be tempted to say that I found the lego head just so I could stop sifting through my feces. My biggest concern is that the lego head wasn’t marked in any way. How do we know that it was the same lego head that was swallowed at the beginning of the trial, and not just a different lego head that they had as a snack a week earlier, or maybe even from their own childhood?

Bottom line: A great study from an even better group of folks. I truly hope that get some ignoble award traction on this one.

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3 papers, 1 question: What is the best airway strategy during cardiac arrest?

Benger JR, Kirby K, Black S, et al. Effect of a Strategy of a Supraglottic Airway Device vs Tracheal Intubation During Out-of-Hospital Cardiac Arrest on Functional Outcome: The AIRWAYS-2 Randomized Clinical Trial. JAMA. 2018; 320(8):779-791. PMID: 30167701

This is the AIRWAYS2 trial, a pragmatic, cluster randomized trial comparing LMA to intubation in out of hospital cardiac arrest. They randomized 9296 patients, and there was no difference in the primary outcome of survival with good neurologic function.

The full write up can be found here.

Jabre P, Penaloza A, Pinero D, et al. Effect of Bag-Mask Ventilation vs Endotracheal Intubation During Cardiopulmonary Resuscitation on Neurological Outcome After Out-of-Hospital Cardiorespiratory Arrest: A Randomized Clinical Trial. JAMA. 2018; 319(8):779-787. PMID: 29486039

This is another pragmatic multicentre RCT, this time comparing BVM to intubation for adult out of hospital cardiac arrest. This study occurred in France and Belgium, where physicians are part of the EMS crew. They randomized 2043 patients, and there was no difference in the primary outcome of neurologically intact survival at 28 days.

The full write up can be found here.

Wang HE, Schmicker RH, Daya MR, et al. Effect of a Strategy of Initial Laryngeal Tube Insertion vs Endotracheal Intubation on 72-Hour Survival in Adults With Out-of-Hospital Cardiac Arrest: A Randomized Clinical Trial. JAMA. 2018; 320(8):769-778. PMID: 30167699

This is a multicentre cluster randomized trial comparing laryngeal tube airway to intubation in out of hospital cardiac arrest. They randomized 3004 patients, and found that laryngeal mask was superior to intubation for their primary outcome of survival to 72 hours. It also looks better in terms of longer term survival with good neurologic function.

The full write up can be found here.

Overall Bottom Line: I have never been a big fan of intubation during cardiac arrest (unless there is reason to believe that the airway was a primary cause of arrest). Although none of these trials is perfect, they all seem to support the idea that intubation is not required. Although the outcomes are essentially equivalent, when you consider ease of use, complications, and training, I think a supraglottic airway is the clear first line option in most cardiac arrest patients.

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Suction not working? That sucks

Shah K, Weingart S. Suction tubing reversal as a dormant failure during airway management. The American Journal of Emergency Medicine. 2018; 36(12):2336.e3-2336.e4. PMID: 30177268

This is just a case report, but it discussed a really important safety issue that I wasn’t aware of until a discussion with Scott a couple months ago. They discuss a case in which they had two appropriately checked suction devices ready before intubation, but that failed during the intubation procedure. If you look at a standard suction canister, there are two ports that suction tubing can be connected to: one directly in the middle, and one more peripherally. The central one is supposed to be connected to the wall, while the peripheral one should be connected to the Yankauer (or preferably something wider, like a Ducanto). If you reverse these connections, the suction will work normally when you test it. However, the central port has an absorbent piece of foam in it that will stop the suction as soon as it gets wet. (Designed to stop biohazard materials from making it to the wall suction). Interestingly, they report that the sound of the suction didn’t change, so it wasn’t obvious why the suction wasn’t working. Ideally, this problem should be fixed at a systems level (it shouldn’t be possible to hook these up backwards). For now, though, the only fix is to be vigilant about the set up before you get to the point when you really need the suction.

Bottom line: There is a right and a wrong way to connect suction, and the difference is important. Check it before it becomes an issue.

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Last airway paper: Stop using cricoid pressure

Birenbaum A, Hajage D, Roche S, et al. Effect of Cricoid Pressure Compared With a Sham Procedure in the Rapid Sequence Induction of Anesthesia: The IRIS Randomized Clinical Trial. JAMA surgery. 2018; PMID: 30347104

This is the best study we have to date looking at cricoid pressure. It is a double blind, sham controlled RCT in 3472 OR patients undergoing RSI. There was no difference in the rate of aspiration. Cricoid pressure made intubation more difficult. In other words, cricoid pressure is harmful and should be abandoned if you are still using it routinely.

The full write up can be found here.

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Usually insufflated drugs cause tachydysrhythmias. Now there is an intranasal option to stop them?

Stambler BS, Dorian P, Sager PT, et al. Etripamil Nasal Spray for Rapid Conversion of Supraventricular Tachycardia to Sinus Rhythm. Journal of the American College of Cardiology. 2018; 72(5):489-497. PMID: 30049309 [free full text]

This is a cool little RCT. You might not find it that useful, as it is only a phase 2 study and the medication discussed isn’t actually available yet, but the product looks interesting, and the paper also ties into my firm belief that calcium channel blockers are clearly better for the management of SVT. This is a multi-center, double-blind, placebo controlled dose-ranging study. They included 104 adult patients with documented histories of SVT who were scheduled to have catheter ablations. In the electrophysiology lab, they induced SVT using either pacing or isoproterenol, and then used either placebo or intranasal etripamil (a calcium channel blocker) at 1 of three doses. SVT was terminated in 35% of the placebo group, and 65%, 87%, 75%, and 95% of the patients getting etripamil (at doses of 35 mg, 70 mg, 105 mg, and 140 mg respectively). The medication was effective by about 3 minutes. There were definitely more side effects in the medication group (80% vs 20%), but the side effects don’t sound all that bad. Blood pressure didn’t drop with the lower doses, but fell by about 20 mmHg in the higher doses. I would want to see a proper, large phase 3 trial before making statements about the net benefit versus harm. Also, before we start using the presumably expensive new intranasal version, we should probably see it compared to an oral calcium channel blocker. Obviously, these are not emergency department patients, and inducing SVT with isoproterenol might be different than naturally occuring SVT, limiting external validity. They screened 199 patients to get the 104, so selection bias is also possible.

Bottom line: Not ready for prime time (and not even available yet), but keep your eye out for alternative ways to give the best SVT medications: calcium channel blockers

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Are we overdoing insulin?

LaRue HA, Peksa GD, Shah SC. A Comparison of Insulin Doses for the Treatment of Hyperkalemia in Patients with Renal Insufficiency. Pharmacotherapy. 2017; 37(12):1516-1522. PMID:28976587

This is a single-center chart review. They looked at the outcomes of patients treated with either 10 units or 5 units of IV insulin to manage hyperkalemia. They were pretty confident they identified the appropriate patients, because at this institution push dose insulin is only allowed for the treatment of hyperkalemia. They have a protocol that 25 grams of dextrose is given at the same time as the insulin (either IV or oral) and repeated 1 hour later, with a third dose at 3 hours if needed. After some exclusions, they identified 133 patients who were treated with 5 units of insulin and 542 who were treated with 10 units. As these patients weren’t randomized, we should expect confounders, and not surprisingly, the baseline blood glucose was lower in the group in whom physicians decided to use 5 units. The primary outcome was hypoglycemia, and occured in 20% of the 5 unit group and 29% of the 10 unit group. (Both these numbers seem high to me). Both groups saw their potassium drop by the same amount (1.0 mEq/L). Obviously, if the drop in potassium is the same in both groups, it makes sense using the lower dose. The methodological problems with a chart review mean we can’t say anything definitive here, and I will probably keep using 10 units simply because hyperkalemia is so dangerous. (I also think it is reasonable to change practice, starting with 5 units, but adding more if you aren’t seeing adequate shift). However, this study does serve as a nice reminder that we need to be more cognizant of the hypoglycemia that will inevitably follow our push dose insulin.

Bottom line: 5 units of IV push insulin might be as effective as 10 units in the management of hyperkalemia, with fewer side effects, but I want to see more data.

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A RCT of parachutes!

Yeh RW, Valsdottir LR, Yeh MW, et al. Parachute use to prevent death and major trauma when jumping from aircraft: randomized controlled trial. BMJ (Clinical research ed.). 2018; 363:k5094. PMID: 30545967 [free full text]

Finally, we have the much anticipated, previously thought to be impossible, RCT examining parachutes. (We also close as we began, with the individuals willing to experiment on themselves for the betterment of science). They ran an RCT in which individuals jumping out of aircraft were randomized to either a parachute or just an empty backpack. There was no difference in the outcomes! Of course, the mortality rate was 0% because these aircraft were firmly on solid ground and not moving. Overall, a fun look into some of the shortcomings with evidence based medicine.

The full write up can be found here.

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Cheesy Joke of the Month

Staying calm is so important in medicine, because when doctors get angry, they lose their patients.